Wooden flooring is usually supplied as boards having tongue-and-groove edges, such that the floor is laid over a subfloor by placing the boards next to each other, forcing the tongue on the edge of one board into the mating groove of the next, and nailing the boards in place through the edge, so that the nails are invisible when the next board is installed. Forcing the tongues into the grooves requires a fair amount of force, and the boards must be held tightly together as the nails are driven.
Traditionally the installation and repair of wooden flooring has required two carpenters. To assure a tight fit between the individual pieces of flooring the first carpenter forces the flooring being installed or repaired into proper position, while the second carpenter securely fastens the flooring being held to the subfloor. To insure that the floor is held tightly together it has generally been the situation that nails are driven into the flooring used at an angle so that as the nail engages with the subfloor, the individual pieces of flooring are driven laterally into a tighter abutment with the piece of flooring previously put in place. In this manner the flooring is constructed, one piece at a time, gradually being laid from the base of a starting wall towards the base of an ending wall where the last piece will be put in place.
A number of devices have been developed in the past to aid in the installation of flooring, but they have had a number of deficiencies which make them difficult to use in the modern method of installation on a subfloor.
Examples of these prior art flooring clamps or jacks are Parrish, "FLOOR CLAMP" U.S. Pat. No. 10,061, issued in 1853; Foster, "FLOOR-CLAMPS", U.S. Pat. No. 136,428, issued in 1873; or Lassahn, "CLAMPING DEVICE FOR CONSTRUCTING FLOORING, DECKING AND THE LIKE", issued in 1964. All of these devices force the flooring into alignment using screw (Parrish), rack-and-pinion (Foster) or hydraulic (Lassahn) force exerted against the floor joists. Obviously, this would not work if the floor is being installed in the present manner over a plywood subfloor.
Masters, "PUSH STICK FOR PLUMB AND LINE ADJUSTMENT OF STUD WALLS", U.S. Pat. No. 4,660,806, issued in 1987, is a more general pushing device using a hydraulic ram, but is not used for flooring.
Powernail Co. Inc, P.O Box 300, Lincolnshire, Ill. 60069, currently markets two models of a flooring jack called a Powerjack.TM.. Both use a ratchet mechanism to exert force on flooring. The Powerjack 100 has a bent leg which hooks over the edge of the tongue-in-groove flooring and a flat pressor foot moved by a ratchet. The unit rides on the flooring to be moved, while the pressor foot pushes against a stationary object such as a wall or a stud nailed to the subfloor, thus pulling the flooring into place. The Powerjack 200 is designed for glue down and gym floor installation by pushing from a subfloor anchor point. It has a flat foot which must be attached by nails or screws to the subfloor, and a second foot which can be moved by a ratchet to press against the tongue-in-groove flooring. Both have relatively restricted maximum distances from their anchor points, and, unless used right next to a wall in the case of the model 100, both require some sort of anchor attached to the subfloor.